I just mounted the n flow and was wondering which outlet I should run to the overflow bottle? Thanks!

 

The thermostat neck is higher, so I'd probably use it.
However you do it...the port you use for the overflow gets the pressure relief cap, the other one gets a fixed cap.

 

Pressure relief cap has the lever? I noticed it is a 13# compared to the fixed 16#. Thank you.

 

No, the lever is a design feature but has nothing to do with the type of cap.
Your 13 psi cap is the one for the overflow port (presumably the thermostat neck), the rad should have a cap that doesn't open at all.

 

Just curious, but what's the harm in using two pressure relief caps?

 

Nothing really. However, what if the cap that opens first is the one that doesnt have the overflow connected? It will just spew coolant all over the place.

I am pretty sure that two 13lb caps will open at different pressures. One WILL open before the other.

 

you would need to Y the overflow hoses together into the overflow tank, but other than that its fine.

 

I'm running a twin turbo 300zx rad cap for the neck and radiator. I could just go buy a Y and run both. At the moment I have a cap on the neck with a hose clamp. I have not run the car yet with the new rad.

 

The Flat cap is NOT supposed to have a Nipple to overflow.They make this very part for that Flat cap setup.Here is the link.:https://www.rx7club.com/comments-sug.../#post11245846
addressing the second part.
I have 2 relief caps on my setup,hoses connect and are T'eed to the overflow.
I have had absolutely Zero issues in 3 years with this.
I'd rather have 1 out of 2 caps open than ONE out of 1 NOT open.